More conditioning, less game minutes?

conditioning, yes. more game minutes increases rate of improvement.

Just conditioning. Also, I would put importance of durability as probably the very last thing to even think about. Injuries do happen but are rare enough and random enough to just not worry about. At All.

I suppose, technically, a person could start a player and risk giving him maximum minutes so his Work Ethic would rise a little faster which would then increase his possible conditioning practice. Now, I know I'm a bad coach, but this strategy seams even less effective than my "whirling egg-beater of death" motivational speeches I give to my team.

Durability doesn't effect the odds of an injury but rather their recovery speed.

The odds of getting injured seems to be completely random and exceedingly low. I feel like one guy gets hurt for my teams every 10 seasons. 

On top of that it doesn't seem to effect the extent of the injury, which also seems to be random. I've seen 90+ durability guys have injuries to drop them into the 40s and 10 durability guys dropped into the 90s.

The place it effects it is if you have a low durabiltiy guy get dropped into the 50 he'll recover slowly and you might as well consider him out for season.

Durability is nearly meaningless to the point that you should basically ignore it completely.

Thank you

The injuries for the most part aren't a big deal, but I notice if I'm running a short rotation and guys are playing well into their fatigue levels I will see injuries. I havent lost any players for any amount of time (other than in the game they are hurt) but I do get the message from the doc talking about benefiting from rest - the guys are usually 80+ percent after the game and can still play.